Japanese Patent Application Laid-Open No. 2007-28855 discloses an armature. The armature has teeth, a yoke, and coils. The teeth are arranged annularly around an axis. The yoke has through holes allowing the teeth to be inserted therethrough in an axial direction. The coils are wound on the teeth. The through hole opens at the inner circumferential side in a radial direction. This reduces eddy currents occurring in the yoke due to magnetic fluxes flowing in the teeth in the axial direction.
In order to prevent the teeth from falling out of the yoke along the axial direction and to improve the strength of the armature, the teeth, the yoke, and the coils are integrally resin-molded. For the resin-molding, the teeth, the yoke, and the coils are accommodated in a predetermined die, and a resin is poured therein and cured. Note that as the documents related to the present application, there Patent Documents 2 and 3 are further given: Japanese Patent Application Laid-Open No. 2007-28854 and International Publication WO03/047069.